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A Diabetic-Like Condition of Turkey Embryos Maintained in Shell-Less Culture

1989; SAGE Publishing; Volume: 190; Issue: 4 Linguagem: Inglês

10.3181/00379727-190-42867

1535-3702

J. P. McMurtry, Mark P. Richards, R.W. Rosebrough, N. C. Steele,

Organ and Tissue Transplantation Research

Serum insulin concentration and pancreatic insulin content were determined for turkey embryos incubated in ovo and in long-term shell-less culture (ex ovo). Insulin was undetectable (< 10 pg) in serum from 87% of the ex ovo embryos compared with their in ovo counterparts. This was evident at all incubation ages, although insulin was detectable in more of the ex ovo embryos on Day 24. Insulin increased in the embryos incubated in ovo from 122 (Day 15) to levels exceeding 2000 pg/ml at hatching. Total pancreatic insulin content was greater in the cultured embryos on Days 15, 17, and 22 compared with their in ovo counterparts. Serum glucose was significantly greater (P < 0.05) in the ex ovo embryos at all ages. In response to an infusion of l-arginine, serum insulin increased from 566 to 1256 pg/ml in the in ovo embryos, whereas no change was evident in the ex ovo embryos (233 vs 257 pg/ml). When embryos incubated in ovo were injected with insulin, a significant (P < 0.05) reduction of serum glucose was observed at 60 min after injection. Serum glucose concentrations remained elevated in the embryos incubated ex ovo despite the insulin injection. Liver glucose 6-phosphatase activity, assessed on Days 15 and 22 of incubation, was found to be significantly (P < 0.05) lower in the ex ovo embryos. Turkey embryos incubated in shell-less culture exhibited chronic hyperglycemia in concert with extremely low circulating levels of insulin. The pancreatic beta cells of these embryos were not responsive to arginine or elevated glucose. Taken together these findings suggest the occurrence of a diabeticlike condition in the ex ovo embryos. This defect in insulin secretion may, in part, be responsible for some of the developmental abnormalities characteristic of the turkey embryo cultured ex ovo.